Quillon

On a sword, the crossguard, or cross-guard, also known as quillons, is a bar of metal at right angles to the blade, placed between the blade and the hilt. The crossguard was developed in the European sword around the 10th century for the protection of the wielder's hand. The earliest forms were the crossguard variant of the Spatha used by the Huns, the so-called Pontic swords. The crossguards were not only used to counter enemy attacks, but also to get a better grip on the sword. They were later seen in late Viking swords, and is a standard feature of the Norman sword of the 11th century and of the knightly arming sword throughout the high and late medieval period. Early crossguards were straight metal bars, sometimes tapering towards the outer ends. While this simple type was never discontinued, more elaborate forms developed alongside it in the course of the Middle Ages. The crossguard could be waisted or bent in the 12th and 13th century.

Beginning in the 13th or 14th century, swords were almost universally fitted with a so-called chappe or rain-guard, a piece of leather fitted to the crossguard. The purpose of this leather is not entirely clear, but it seems to have originated as a part of the scabbard, functioning as a lid when the sword was in the scabbard.

In the 14th to 15th century, many more elaborate forms were tried. A feature of such late medieval forms is the cusp or écusson, a protrusion of the crossguard in the center where it is fitted on the blade. Also from the 14th century, the leather chappe is sometimes replaced with a metal sheet. An early example of this is a sword dated to c. 1320–40 kept at the Kelvingrove Museum in Glasgow. A later example is the "Monza sword" of Estore Visconti (early 15th century), where the rain-guard is of silver and decorated with a floral motif.

After the end of the Middle Ages, crossguards became more elaborate, forming first quillons and then, through the addition of guard branches, the basket hilt, which offered more protection to the unarmored hand.

Ewart Oakeshott in chapter 4 of his The Sword in the Age of Chivalry (1964) classifies medieval cross-guards into twelve types:

The medieval dagger in the 14th and 15th century also adopted a variant with quillons, styled after the hilt of a sword. Quillon-daggers remained popular in the 16th century, after the sword type it resembled had fallen out of use.

...
Wikipedia